1 /* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * locks.c
5 *
6 * Userspace file locking support
7 *
8 * Copyright (C) 2007 Oracle. All rights reserved.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public
12 * License as published by the Free Software Foundation; either
13 * version 2 of the License, or (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public
21 * License along with this program; if not, write to the
22 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 * Boston, MA 021110-1307, USA.
24 */
25
26 #include <linux/fs.h>
27 #include <linux/fcntl.h>
28
29 #include <cluster/masklog.h>
30
31 #include "ocfs2.h"
32
33 #include "dlmglue.h"
34 #include "file.h"
35 #include "inode.h"
36 #include "locks.h"
37
ocfs2_do_flock(struct file * file,struct inode * inode,int cmd,struct file_lock * fl)38 static int ocfs2_do_flock(struct file *file, struct inode *inode,
39 int cmd, struct file_lock *fl)
40 {
41 int ret = 0, level = 0, trylock = 0;
42 struct ocfs2_file_private *fp = file->private_data;
43 struct ocfs2_lock_res *lockres = &fp->fp_flock;
44
45 if (fl->fl_type == F_WRLCK)
46 level = 1;
47 if (!IS_SETLKW(cmd))
48 trylock = 1;
49
50 mutex_lock(&fp->fp_mutex);
51
52 if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
53 lockres->l_level > LKM_NLMODE) {
54 int old_level = 0;
55
56 if (lockres->l_level == LKM_EXMODE)
57 old_level = 1;
58
59 if (level == old_level)
60 goto out;
61
62 /*
63 * Converting an existing lock is not guaranteed to be
64 * atomic, so we can get away with simply unlocking
65 * here and allowing the lock code to try at the new
66 * level.
67 */
68
69 locks_lock_file_wait(file,
70 &(struct file_lock) {
71 .fl_type = F_UNLCK,
72 .fl_flags = FL_FLOCK
73 });
74
75 ocfs2_file_unlock(file);
76 }
77
78 ret = ocfs2_file_lock(file, level, trylock);
79 if (ret) {
80 if (ret == -EAGAIN && trylock)
81 ret = -EWOULDBLOCK;
82 else
83 mlog_errno(ret);
84 goto out;
85 }
86
87 ret = locks_lock_file_wait(file, fl);
88 if (ret)
89 ocfs2_file_unlock(file);
90
91 out:
92 mutex_unlock(&fp->fp_mutex);
93
94 return ret;
95 }
96
ocfs2_do_funlock(struct file * file,int cmd,struct file_lock * fl)97 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl)
98 {
99 int ret;
100 struct ocfs2_file_private *fp = file->private_data;
101
102 mutex_lock(&fp->fp_mutex);
103 ocfs2_file_unlock(file);
104 ret = locks_lock_file_wait(file, fl);
105 mutex_unlock(&fp->fp_mutex);
106
107 return ret;
108 }
109
110 /*
111 * Overall flow of ocfs2_flock() was influenced by gfs2_flock().
112 */
ocfs2_flock(struct file * file,int cmd,struct file_lock * fl)113 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl)
114 {
115 struct inode *inode = file->f_mapping->host;
116 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
117
118 if (!(fl->fl_flags & FL_FLOCK))
119 return -ENOLCK;
120 if (__mandatory_lock(inode))
121 return -ENOLCK;
122
123 if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
124 ocfs2_mount_local(osb))
125 return locks_lock_file_wait(file, fl);
126
127 if (fl->fl_type == F_UNLCK)
128 return ocfs2_do_funlock(file, cmd, fl);
129 else
130 return ocfs2_do_flock(file, inode, cmd, fl);
131 }
132
ocfs2_lock(struct file * file,int cmd,struct file_lock * fl)133 int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl)
134 {
135 struct inode *inode = file->f_mapping->host;
136 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
137
138 if (!(fl->fl_flags & FL_POSIX))
139 return -ENOLCK;
140 if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
141 return -ENOLCK;
142
143 return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl);
144 }
145